A nitride semiconductor light emitting device has been highly developed in terms of design and manufacturing technology, thereby contributing to improvements in efficiency and output of white light emitting diodes (LEDs), as well as blue, green and ultraviolet (UV) short-wavelength LEDs. As a result of these developments, the applications of nitride semiconductor light emitting devices have been extended to headlamps of vehicles and general lighting devices. Accordingly, there is a need for a reduction of manufacturing costs in order to substitute existing light sources such as fluorescent lamps and the like.
In order to improve manufacturing yields, research is being conducted to replace a sapphire substrate with a wafer formed of a different material, such as a silicon substrate or the like, which is relatively cheap and able to have a large diameter. In this regard, development is needed in methods of securing crystalline properties in nitride single crystals grown on a substrate and improving light emitting efficiency by preventing photons generated in an active layer from being absorbed by the substrate.